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Alex Samano
April 30, 2025

Ultimate Guide to Performance Opti Rigging

Optimist
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When it comes to dinghy lines, it’s a game of optimizing for performance and durability. For most lines, performance comes down to hold, stretch, float, and weight (including water hold), while durability comes down to fraying. Most marine rope used for dinghy sailing will not break without fraying first. So, a few things to consider when making decisions about rigging.

  1. Safety should always be first. Always use the proper materials. When critical lines fail (usually in high wind), your sailor will likely lose control of the boat - rigging is safety.
  2. The longest lines will lead to the most weight. In Opti sailing, the painter line and the mainsheet make the biggest weight difference. Make sure they are light and do not retain water.
  3. Watch for hold at the cleats. Lines get stiff as they get older, and they do not hold the same in a cleat. In Opti, this is particularly true with the Sprit Halyard and the Boom Vang. They tend to get salty and eventually lose hold. You can prevent it by always rinsing the lines and don’t hesitate to replace them when needed. You can keep the cleats sharp with a small file.

About the Main and Tapered Lines

This is a common topic of conversation, so lets cover it first. A thicker mainsheet is always easier to hold. Don’t underestimate the value of an 8 mm main when the wind hits 20 knots. After 4 races in a standard IODA course, your sailor will have spent 2 hrs. sailing upwind. You try to hold on to a 6 mm line for 2 hrs. in 20 knots. Their forearms will burn, their fingers will cramp, and their hands will get raw. An 8 mm line with well-placed knots is a lifesaver. In practical terms, the ideal main sheet performance would be as follows:

  1. Easy flow in low winds when a sailor is gybing. A thicker line in low-wind conditions needs force to move through the block. Your sailor has to throw the sail harder to complete the gybe.
  2. Easier grip in high-wind conditions. A thicker line is easier to hold in high winds, especially for older sailors (bigger hands). It is also much less likely to feed back into the main block and jam (yes, it happens with thinner lines).
  3. No water retention, soft grip, no hardening. The mainsheet will constantly be in salt water. If it absorbs water, it becomes heavy and will eventually fill with salt. This salt hardens the material, making it harder to grip. Additionally, the salt acts as an abrasive, which can tear the skin. Double core lines often have less flexibility, which makes them less soft and more likely to hold water between their layers.

From experience, we find that the best way to accomplish the above is by using a 4:1 setup with an 8mm line in high-wind and a 3:1 (or 2:1) setup with a 6mm line in low-wind. When in doubt, always go with the higher wind setup. We also find that the New England Ropes Bzzz Line offers the best performance. It helps a lot if you throw it into your washing machine once a season and make sure to rinse it with the boat after each regatta. Tapered lines are very popular, but we don’t recommend them. The purpose of them is to have a thinner line flow through the blocks easily and a thicker line in the hands of the sailor. Unfortunately, there is no design where this is possible when the sailor is fully sheeted-in (upwind) and with a fully open sail (downwind). Either the thicker line goes into the blocks when fully open, or the thinner line is on the hands of the sailor when sheeted in. In addition, we find the material of most tapered lines to be hard, absorb water, and have low abrasion resistance.

Recommended Optimist Line Types and Dimensions

In general, Marlow, New England Ropes, Robline, or Samson are reputable brands that manufacture ropes for dinghies. Some lines need to be highly friction-resistant, while others must withstand significant tension (such as the boom vang) and maintain very low stretch. Consequently, low-stretch materials like Dyneema, Vectran, Spectra, and Kevlar are frequently employed in sailing rigging. For areas requiring friction resistance, Polyester and Kevlar are commonly utilized. While some of these materials exhibit low-friction properties, they vary based on the specific material and application, and they are frequently used in line covers as well.

Sail and Mast Lines

The most common and most frequently lost lines, sail ties should be always available.

# Line Use Material Diam. Len. No. Notes Recommendations
1 Sail Lacing Ties They hold the sail to the mast and boom for safety. Vectran or Dyneema - no stretch. 1.2 mm 20 in. 12 Each side of the sail takes 6 sail ties.
2 Sail Corner Ties They hold the sail in place at the 3 corners of the sail. Vectran or Dyneema - no stretch. 3 mm 20 in. 5 Each corner uses two lines except the sail clew, which only has one. The top of the mast lines include a hold and a limiter (at an angle).

Sprit Halyard Lines

These are the sprit system lines, they should all remain attached to the mast at the cleat.

# Line Use Material Diam. Len. No. Notes Recommendations
3 Sprit Halyard - Sprit End This is the line that runs through the block on hook and connects to the sprit pole. Dyneema or Vectran - no stretch. 4 mm 36 in. 1 If you want, you can use a shorter length of this line with a spliced eye and a tiny shackle.
4 Sprit Halyard - Cleat End This is the control line that runs from and to the halyard cleat. It needs to be able to hold in the cleat and have a bit of grip. 4 mm 60 in. 1 If it slips too much at the cleat, change it. It’s usually slippery because of salt.

Boom Lines

The boom has the most lines and they should all be permanently attached to it.

# Line Use Material Diam. Len. No. Notes Recommendations
5 Boom Limiter This is the small line that goes between the boom and the mast and keeps it from moving further down. Vectran or Dyneema - no stretch. 3 mm 8 in. 1 This line lasts forever, unlikely you will need to replace it. Set it once and leave it alone.
6 Boom Vang - Boom End This is the line that goes through the eye and around the boom. Vectran 12-strand single braid. 2 mm (1/8 in) 12 in. 1 Don’t worry about the line being small, it’s Vecran. It will literally never fail. Specially, because there is no friction. If you want, you can use two lines for safety.
7 Boom Vang - Cleat End This is the control line that goes through the cleat. Vectran or Dyneema core, plus a cover. These types of lines are known as control lines. 5 mm 40 in. 1 The boom cleat frays lines frequently (due to the bend). For this application, the ROBLINE Dingy control and any 4mm control line do not last. So, go with 5mm and a 16.
8 Outhaul (Tapared) The line at the clew of the sail (back corner) tensioning the sail to the boom. For a tapered line, it needs a Vectran or Dyneema core plus a cover. These types of lines are known as control lines. 4 mm 5 ft. 1 You need about 3 ft. of tapering using the inside braided core and 2 ft. of the outside cover to go into the cleat.
9 Boom Bridle The line that goes on the boom that holds the bridle ring(s) where the main block attaches. Dyneema or Vectran core. The line mustn’t stretch. This type of line is referred to as a Lashing line. 3 mm 5 ft. 1 The IODA rules do not allow for a movable ring. Instead, you can put more than one fixed ring on the bridle. More than a 4 mm diameter will not fit through the boom eye.

Haul Lines

These lines are attached to the haul and cover the hiking straps, dagger board, tow line, and attaching loose items to the haul.

# Line Use Material Diam. Len. No. Notes Recommendations
10 Safety Lines Shock Cord These are the lines to secure the Bailers, Paddle, and Dagger board to the boat in case of capsize. Sailing shock-cord. 4 mm (5/32 in) 36 in. 4 You don’t need more than 4mm in diameter. It gets bulky on the boat. Marine shock is usually UV resistant.
11 Hiking Straps Tension Line This is the line that connects the straps to the boat, and it’s used to set the tension of the straps. Vectran or Dyneema - no stretch. 3 mm 32 in. 1 You should be able to go around 3 times and have enough line to tie it firmly. So, just double the corner tie length.
12 Painter or Bow/Tow Line It’s the line that will be used to tow the boat. Must float, not retain water, and be kink resistant. 6 mm 27 ft. / 8 m. 1 If you are trying to take weight off the boat, we recommend the Simmons Bowline - super light and ZERO water hold. Just know, it will fray in 1-2 seasons but will not splinter. The class legal length is 8m.
13 Dagger Board Shock Cord This is the line that holds the straps and holds the dagger board down. Dyneema covered shock-cord. 6 mm 6 ft. 1 Don’t use a shock-cord thicker than 6mm, it will not fit into the eye in the bow side of the dagger box.
14 Dagger Board Shock Cord Hold The small line running aft (behind) of the dagger board to hold the shock cord in the stern. Vectran or Dyneema - no stretch. 3 mm 32 in. 1 This small line will always be under tension, it must be of good quality and not stretch.

Block and Main Sheet

# Line Use Material Diam. Len. No. Notes Recommendations
15 Mainsheet Block Extender It’s the line that runs between the shackle and the main block. Vectran or Dyneema - no stretch. 4 mm 13 in. 1 Using an extender reduces the amount of sheet in the boat, making it quicker to accelerate and less likely to get tangled.
16 Mainsheet It’s the main line your sailor will use to control the sail. A thicker diameter is easier to hold for bigger sailors. Must not retain water and should not be abrasive. We highly recommend the Bzzz dinghy lines. 6 to 8 mm 26 ft. (4:1 capable) 1 We don’t recommend tapered lines (expensive and crapy). Instead, we recommend using a 6mm line for low wind and an 8mm line for high wind. Go with a 26’ length to fit 4:1 setups.

What to Carry on Your Toolbox?

Now that we have all the lines and types identified, here is a summary of the items you can carry in your box that will take care of replacing any line in your Optimist. Specially, for coaches and other folks who oversee a fleet of boats. We go with ROBLINE and MARLOW, because they are generally available in all the different sizes and types we need, but you can get any brand you prefer or can find.

Carry With: Used at Most Events

These items need replacement or get lost at every event. We would recommend a supply roll handy. You will likely use it at every regatta. Most are not fixed or tend not to last very long.

  1. MARLOW: 1.5mm Excel Vecran® Core / 16 Plait Polyester Cover: Sail Lacing Ties (1)‍
  2. MARLOW: 3mm Excel Vecran® Core / 16 Plait Polyester Cover: Sail Corner Ties (2), Boom Limiter (3), Hiking Straps Tension Line (5), Dagger Board Shock Cord Hold (14)‍
  3. ROBLINE: 4mm Dyneema Shock-Cord: Safety Lines for Bailers, Paddle, Dagger Board, and Water Bottle. (4)

Keep at Home: Frequently Used

These items need replacement once or twice a season. We recommend having some material handy, but you can keep it at home.

  1. ROBLINE: 4mm Ocean 3000 Dyneema 12 Strand, Single Braid: Mainsheet Block Extender (6), Sprit Halyard - Sprit End (15)‍
  2. ROBLINE: 3mm Ocean 3000 Dyneema 12 Strand, Single Braid: Boom Bridle (10)‍
  3. ROBLINE: 2mm Ocean 3000 Dyneema 12 Strand, Single Braid: Boom Vang - Boom End (7)‍
  4. ROBLINE: 5mm Dinghy PolyTech Line: Boom Vang - Cleat End (8)‍
  5. ROBLINE: 4mm Dinghy PolyTech Line: Outhaul Tapered (9), Sprit Halyard - Cleat End (16)

Buy As Needed: Will Likely Last the Ownership of the Boat

These items need replacement once or twice a season. We recommend having some material handy, but you can keep it at home.

  1. NEW ENGLAND ROPES: Bzzz Dinghy Braid 5/16 or 8mm (high-wind): Mainsheet 8mm (11, high-wind)‍
  2. NEW ENGLAND ROPES: Bzzz Dinghy Braid 9/32 or 6mm (low-wind): Mainsheet 6mm (11, low-wind)‍
  3. SIMMONS Boat Works: Painter / Bowline: Painter or Bow/Tow Line (12)‍
  4. ROBLINE: 6mm Dyneema Covered Shock-Cord: Dagger Board Shock Cord (13)

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